Re: [PATCH 0/7] disable bridge ari forwarding after connected ari device hot removed

[Jiang Liu <jiang.liu@huawei.com>]

When scanning PCI devices for hot-add, it guarantee function 0 is scanned
at first. And when destroying PCI devices for hot-removal, we also need to
destroy function 0 at last, but currently there's no such guarantees. 

On 2012-10-9 15:42, Yijing Wang wrote:
> On 2012/10/9 11:42, Jiang Liu wrote:
>> How about this patch, which disables ARI when adding new PCI devices?
>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>> index 5485883..c841aa6 100644
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -2016,13 +2016,14 @@ void pci_free_cap_save_buffers(struct pci_dev *dev)
>>  void pci_enable_ari(struct pci_dev *dev)
>>  {
> 
> I think it's ok. Delay to disable ARI until next hot add is safe.
> Maybe rename as pci_configure_ari is better.
> 
>>         u32 cap;
>> +       bool enable = true;
>>         struct pci_dev *bridge;
>>
>>         if (pcie_ari_disabled || !pci_is_pcie(dev) || dev->devfn)
>>                 return;
>>
>>         if (!pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI))
>> -               return;
>> +               enable = false;
>>
>>         bridge = dev->bus->self;
>>         if (!bridge)
>> @@ -2032,8 +2033,15 @@ void pci_enable_ari(struct pci_dev *dev)
>>         if (!(cap & PCI_EXP_DEVCAP2_ARI))
>>                 return;
>>
>> -       pcie_capability_set_word(bridge, PCI_EXP_DEVCTL2, PCI_EXP_DEVCTL2_ARI);
>> -       bridge->ari_enabled = 1;
>> +       if (enable) {
>> +               pcie_capability_set_word(bridge, PCI_EXP_DEVCTL2,
>> +                                        PCI_EXP_DEVCTL2_ARI);
>> +               bridge->ari_enabled = 1;
>> +       } else {
>> +               pcie_capability_clear_word(bridge, PCI_EXP_DEVCTL2,
>> +                                        PCI_EXP_DEVCTL2_ARI);
>> +               bridge->ari_enabled = 0;
>> +       }
>>  }
>>
>>  /**
>>
>> On 2012-10-9 11:03, Yijing Wang wrote:
>>> pci_enable_ari will be called if an ARI pci device found, then set its bridge ARI Forwarding Enable
>>> bit in Device Control 2 Register. But the bridge ARI Forwarding Enable bit will never be cleared
>>> when an ARI device hot removed.
>>>
>>> my steps:
>>> 1. Hot add an ARI pci device;
>>> 2. Hot remove the ARI pci device;
>>> 3. Hot add an non ARI pci device;
>>>
>>> In this case, after setp 3, we could only find fun 0 of non ARI pci device because of its bridge ARI Forwarding Enable
>>> bit set.
>>>
>>> As PCIe Spec 2.0(6.13/441) recommends:
>>> "Following a hot-plug event below a Downstream Port, it is strongly recommended that software
>>> Clear the ARI Forwarding Enable bit in the Downstream Port until software determines that a
>>> newly added component is in fact an ARI Device"
>>>
>>> This series of patches fix this problem.
>>>
>>> Yijing Wang (7):
>>>   PCI: rework pci_enable_ari for support disable ari forwarding
>>>   PCI, acpiphp: disable ARI forwarding for acpiphp
>>>   PCI, pciehp: disable ARI forwarding for pciehp
>>>   PCI, cpqphp: disable ARI forwarding for cpqphp
>>>   PCI, shpchp: disable ARI forwarding for shpchp
>>>   PCI, sgi: disable ARI forwarding for sgiphp
>>>   PCI, ibmphp: disable ARI forwarding for ibmphp
>>>
>>>  drivers/pci/hotplug/acpiphp_glue.c     |    1 +
>>>  drivers/pci/hotplug/cpci_hotplug_pci.c |    1 +
>>>  drivers/pci/hotplug/cpqphp_pci.c       |    1 +
>>>  drivers/pci/hotplug/ibmphp_core.c      |    1 +
>>>  drivers/pci/hotplug/pciehp_pci.c       |    1 +
>>>  drivers/pci/hotplug/sgi_hotplug.c      |    1 +
>>>  drivers/pci/hotplug/shpchp_pci.c       |    1 +
>>>  drivers/pci/pci.c                      |   16 +++++++++++-----
>>>  drivers/pci/pci.h                      |    2 +-
>>>  drivers/pci/probe.c                    |    2 +-
>>>  10 files changed, 20 insertions(+), 7 deletions(-)
>>>
>>>
>>>
>>> .
>>>
>>
>>
>>
>> .
>>
> 
>